Obsessional disorder of childhood is a rare disorder about which little is known. The purpose of this protocol is to collect basic data on family history of mental illnesses, sleep measures and neuropsychological testing on a selected group of children and adolescents with obsessional disorder. A drug trial of chlorimipramine, desmethylimipramine and placebo will be carried out to evaluate the effect of antidepressant and the specificity of chlorimipramine for this disorder.